Sewing operations have evolved from a method wherein a sewing machine is fixed and a sheet of cloth is moved on a flat surface so that it is continuously brought into contact with a reciprocating needle, and there has been developed a sewing machine for industrial use which is moved on a sheet of cloth fixed on a flat surface. However, this type of sewing machine has failed to sufficiently perform a variety of sewing operations required for clothes having puffs and the like. In order to solve this, a sewing operation robot has been developed wherein a sheet of cloth is temporarily fixed on a model simulating a human body: a sewing machine is mounted on an industrial robot capable of arbitrarily positioning in a three-dimensional space and causing the needle thereof to assume arbitrary attitudes: and sewing is carried out by moving the sewing machine freely around the model and the like.
Sewing operations include an inching operation wherein seam pitches are repeatedly operated and stopped at very short intervals (during which the needle is moved up and down). However, conventional general-purpose robots have been subjected to vibrations due to insufficient rigidity and have been unusable in some cases.
There is another problem in that sliding friction occurs between the needle and cloth resulting in breakage of the needle due to the increase in the temperature of the needle.
There is still another problem in that the configurations of the mechanical components are enlarged in order to improve the mechanical rigidity of the robot, for which the weight of the robot and the capacity of the motor driving it must be thus increased and, as a result, the configuration is enlarged and the weight of the entire robot is increased.